<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
    <img src="../exam01/validate/validateCode" />
    <script type="text/javascript">
    // 刷新图片  
    function changeImg() {  
        var imgSrc = $("#imgObj");  
        var src = imgSrc.attr("src");  
        imgSrc.attr("src", changeUrl(src));  
    }  
    //为了使每次生成图片不一致，即不让浏览器读缓存，所以需要加上时间戳  
    function changeUrl(url) {  
        var timestamp = (new Date()).valueOf();  
        var index = url.indexOf("?",url);  
        if (index > 0) {  
            url = url.substring(0, url.indexOf(url, "?"));  
        }  
        if ((url.indexOf("&") >= 0)) {  
            url = url + "×tamp=" + timestamp;  
        } else {  
            url = url + "?timestamp=" + timestamp;  
        }  
        return url;  
    }  
    </script>
</body>
</html>